1. Field of the Invention
The present invention relates to a cell-free preparation and process for the microbial solubilization of coal into solubilized coal products. More specifically, the present invention relates to bacterial solubilization of coal into solubilized coal products and a cell-free bacterial byproduct useful for solubilizing coal.
2. Description of Related Art
Thermal and chemical processes for the conversion of coal to liquid and gaseous products generally require somewhat extreme temperature, pressure and chemical conditions. The severity of the operating conditions may commonly include pressures in excess of 3,000 psi and temperatures in excess of 800 degrees Fahrenheit. These processes usually also require a significant capital investment. Because of the relatively mild operating conditions associated with many biological processes, there has been a recurring interest in the potential use of microorganisms for coal processing.
There have been earlier suggestions that microorganisms may be able to solubilize native coal. M. H. Rogoff et al, "The Microbiology of Coal in Bacterial Oxidation of Phenanthrene," J. Bacteriol., Vol. 73, pp. 264-68 (1957); M. H. Rogoff et al, "Microbiology of Coal," U.S. Bureau of Mines, Information Circular 8075 (1962); J. A. Korburger, "Microbiology of Coal: Growth of Bacteria in Plain and Oxidized Coal Slurries," Proc. W. Va. Acad. Sci., Vol. 36, pp. 26-30 (1964). In recent experiments, certain strains of fungi have been shown to produce a liquid product when cultured on the surface of lignite coal in the presence of humid air. M. S. Cohen et al, "Degradation of Coal by the Fungi Polyporous versicolor and Poria monticola," Appl. Environ. Microbiol., Vol. 24, pp. 23-27 (1982); C. D. Scott, G. W. Strandberg, and S. N. Lewis, "Microbial Solubilization of Coal," Biotechnol. Prog., Vol. 2, p. 131 ( 1986). The coal solubilization product is highly polar, water-soluble material of moderately high molecular weight having a high degree of aromaticity. Coal solubilization by these fungi appears, at this time, to be limited to conditions in which the coal must be in contact with aerial mycelia.
Spectroscopic evidence has also been found for the use of coal as a substrate for a bacterial strain of Pseudomonas isolated from a mixed enrichment culture growing in the present of finely ground bituminous coal. Fakoussa et al, "Koehle als Microbielles Substrat unter Aeroben Bedingungen," Kolloquium in der Bergbau-Forschung Gmblt, Essen, pp. 41-49 (1983). Fakoussa et al suggested that both an enzyme and a surface active agent produced by the organism were involved in attacking the coal. Fakoussa et al does not appear to demonstrate that the organism causes both a substantial decrease in the weight of coal and an increase in the carbon content of the culture broth. Fakoussa et al further appears to fail to demonstrate that coal solubilizing activity is produced in the absence of coal.
It is therefore desirable to effect microbial solubilization by using bacteria. It is further desirable to accomplish bacterial solubilization of coal with a submerged bacterial culture that does not require fungal aerial mycelia. It is further desirable to obtain a cell-free substance capable of solubilizing coal since such a substance would significantly enhance potential microbial solubilization techniques.